Figure 1.

Schematic representation of envelope gene products of cloned SIV adapted or not adapted to human cells. SIVmac239 has a full length 164 amino acid cytoplasmic tail (CT) [64]. The 239T construct has a truncated CT of 18 amino acids. A site-specific C to T mutation present in the 239T env gene changed a CAG glutamine codon at position 734 to a TAG termination codon. SIVmac18T contains a single amino acid substitution A239T in the SU domain designated 18 [25]. Numbers represent amino acid residues. Shaded boxes represent the hydrophobic transmembrane-spanning regions.